Preparation of 1, 1, 2-trichloroethane



Patented Dec. 20, 1938 PATENT OFFICE PREPARATION OF LLZ-TRICHLOROETHA NEJohn H. Reilly, Midland, Mich., assignor to The Dow Chemical Company,Midland, Mich., a corporation of Michigan Serial No. 131,977

No Drawing. Application March 19. 1937,

3 Claims.

This invention relates to processes for the preparation of1,1,2-trichloroethane from ethylene chloride.

My improved process for the preparation of 5 1,1,2-trich1oroethanecomprises passing ethylene chloride and chlorine in certain ratios,preferably in the vapor phase, into contactwith molten metal chlorideswhich are at a temperature in the range between about 300 C. and about425 C. The ratio of chlorine to ethylene chloride is preferably in therange between about 0.55 and about 0.75 part by weight of chlorine perpart of ethylene chloride. The ethylene chloride and chlorinemay bepre-heated separately, or

10 in admixture, to any desired temperature up to reaction temperaturebefore they are passed into the molten salt bath.

The bath in which the reaction is carried out comprises one or more ofthe chlorides of aluminum, potassium, iron, sodium, bismuth. zinc, andother metals, such chloride or mixture of chlorides being freely fluidat the reaction temperature. The eutectic produced by mixing 60 parts byweight of aluminum chloride, 30 parts by weight of sodium chloride, and10 parts by weight of ferric chloride is suitable. This eutectic [has amelting point of about 150 C. and a boiling point above 1000 C. Amixture of parts by weight oi sodium chloride and 70 parts by weight ofaluminum chloride is equally suitable. Zinc chloride can be used aloneas the bath. The reaction here involved is exothermic in character andiscapable of developing enough heat to maintain the salt bath attemperatures in the range above given under. ordinary conditions. Infact. cooling may be necessary when high rates of flow of reactants areemployed. The following example illustrates the practice o of myinvention: The bath employed was composed of 36 parts by weight ofpotassium chloride and 84 parts by weight oi. aluminum chloride. It wasapproximately 0 inches in depth and weighed 10.0 pounds. A mixture ofethylene g chloride and chlorine in the ratio of about 0.78

part by weight of chlorine per part oi ethylene chloride wascontinuously led into the bottom 0! said bath at a substantially uniformrate of about mogramsperhounthebathbeingmaim sotainedatatemperatureoiabcutwc.

The gaseous reaction product was cooled'to condense therefrom thechlorinated reaction product, of which 911 grams per hour was collected,and the exit gases were scrubbed with water to recover the hydrogenchloride. The 5 chlorinated product was fractionally distilled and foundto have the following'composition: 1,1,2- trichloroethane 49.5 per centby'weight, dichloroethylenes 7.5 per cent, unreacted ethylene chloride23.2 per cent, and other chloro compounds 10 12.8 per cent. Thisrepresents a yield of 64 per cent of theoretical of1,1,2-trichloroethane, based on the ethylene chloride reacted.

By operating in a like bath at a temperature of about 400 C., and Yachlorine to ethylene l6 chloride ratio of 0.6 to 1.0,I have obtainedresults similar to those shown in the above example.

.Other modes of applying the principle of my invention may be employedinstead of theme explained, change being made as regards the 20 'methodherein disclosed, provided the step or steps stated by any of thefollowing claims or the equivalent of such stated step or steps beemployed.-

I therefore particularly point out and distinctly 5 claim as myinvention: A

1. In a method of preparing 1,1,2-trichloroethane from ethylenechloride, the step which consists in passing chlorine and ethylenechloride, in the ratio of between about 0.55 and about 30 0.75 part byweight of chlorine per part of ethylene chloride, into a bath of moltenmetal chlorides maintained at a temperature between about 300 and about425 C. h

' 2. .In preparing l,1.2-trichloroethane, the steps 35 which consist inpre-heating ethylene chloride to a' temperature not substantially above300 C.. admixing chlorine therewith in the, ratio between about 0.55 andabout 0.75 part by weight of chlorineper part of ethylene chloride, andpass- 40 ing said mixtureinto a bath of molten metal chloridesmaintained at a temperature between about 300 and about 425 C.

3. In preparing 1,1,2-trichloroethane, the step which consists inpassing a mixture consisting of about 0.6 part by weight of chlorine perpart of ethylene chloride into a bath of molten metal chloridesmaintained at a temperature of about JOHN E. REPLY. l0

